1. Field of the Invention
The present invention relates to an image forming apparatus, such as a copier, a multifunction peripheral, a printer, or a fax machine, which is provided with a display portion, such as a liquid crystal panel, and a connection portion (interface) for connection to a keyboard.
2. Description of Related Art
For example, in such image forming apparatuses as copiers and multifunction peripherals, it is sometimes necessary to input characters, symbols, and the like so as to input, for example, a password. Thus, in order to improve convenience at the time of inputting characters and the like, for example, a USB keyboard may be connected to the image forming apparatus, and the image forming apparatus may receive an input of characters and the like made by using the USB keyboard.
For example, there is known an image forming apparatus which includes processing means built in the apparatus, for performing image forming processing based on image data and a controller for controlling a USB device connectable via a USB interface, and which runs a plurality of application programs including an application installed in the controller for performing the image forming processing, in accordance with a required processing condition, and controls the processing means and the USB device to thereby execute processing. In the image forming apparatus, the controller creates a correspondence table that stores information indicating a correspondence between device class information defining the USB device and the application program used for the device, and includes means for updating the information of the correspondence table every time the USB device is connected and managing the information. This configuration is intended to realize, based on an existing technology, a user-friendly input support without difficulty in, for example, inputting a password, even when a user interface function provided to the image forming apparatus is poor.
As described above, when a password input or the like is used in the image forming apparatus, the user may input characters, symbols, numerals, and the like. In recent years, image forming apparatuses such as multifunction peripherals have been provided with such a display portion that has a touch panel (operation panel). Then, for example, the image forming apparatus displays a software keyboard on the display portion so as to receive an input of characters and the like. However, depending on the size of the display portion, each key of the software keyboard may be displayed small. As a result, there occurs such a problem that two or more keys are pressed simultaneously. To address this, as described above, such image forming apparatuses that allow an input of characters and the like to be performed from a connected keyboard are available.
By the way, a keyboard commonly available in the market (for example, USB keyboard) is intended for a personal computer. However, the image forming apparatus is different from the personal computer. Accordingly, the keyboard intended for the personal computer includes such keys that are unnecessary when used for the image forming apparatus (for example, function keys, control keys, and the like). The image forming apparatus only needs to recognize the depression of keys necessary for inputting characters and the like. Then, even if a signal generated when an unnecessary key is pressed is transmitted from the keyboard to the image forming apparatus, the image forming apparatus side ignores the signal. In other words, among the keys of the keyboard, the image forming apparatus handles unnecessary keys as disabled keys.
However, which key is usable and which key is unusable on the keyboard connected to the image forming apparatus are determined by how the image forming apparatus handles a signal transmitted from the keyboard. Thus, there is a problem that a user cannot know which key is usable and which key is unusable. Consequently, the user may perform a needless input operation of pressing an unusable key many times. Hence, there is a problem in respect to usability of the keyboard connected to the image forming apparatus.
Here, the above-mentioned publicly-known technology is intended to provide support in inputting a password or the like even with a poor user interface (UI). However, the publicly-known technology does not take into consideration a case where an unusable key is pressed on the keyboard. Further, for example, confirmation is not made as to whether or not the key is usable, and hence even when a special keyboard is connected, the user may mistakenly recognize that the keyboard is recognized normally by the image forming apparatus.